Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!samsung!zaphod.mps.ohio-state.edu!wuarchive!uunet!hayes!tnixon
From: tnixon@hayes.uucp
Newsgroups: comp.dcom.modems
Subject: Abstracts of papers for upcoming V.fast Meeting
Message-ID: <3736.2796d6db@hayes.uucp>
Date: 18 Jan 91 11:07:07 GMT
Organization: Hayes Microcomputer Products, Norcross, GA
Lines: 62

In a recent mailing, the Special Rapporteur for V.fast in CCITT 
Study Group XVII gave the group a list of papers expected to be 
presented at the upcoming meeting (6-8 Feb 1991 in Ft. Lauderdale).  
The abstracts of the papers give you an idea of the kind of 
proposals that are being presented.  I thought some of you might be 
interested in them.

(1)  IBM/Gottfried Ungerboeck -- Two papers are in process:  (a) A 
new 2-dimensional 64-state non-linear, rotationally-invariant 
trellis coding scheme, which has the feature of being implemented 
with varying degrees of complexity and providing coding gain ranging 
from parity with the 8-state trellis coding as in V.32 to an 
additional improvement of up to 1.2dB;  (b) a candidate startup 
procedure using interleaved tones from opposite ends of the channel 
for channel measurement and moderate (narrow-band QPSK @ 300 baud) 
modulation of interleaved centrally-located tones for data 
communications without the need of echo cancellation.

(2)  Telebit/John Bingham -- Two papers are in process:  (a) Echo 
cancellation, both near and far end, for multicarrier signalling 
combining advantages of data-driven adaptation and signal-driven 
echo emulation.  In order to allow adaption in the frequency domain, 
the echo part of a received signal is made to appear cyclin by tail 
subtraction and cyclic echo construction.  The paper also describes 
methods of compensating for frequency offset in a far echo, and for 
fast initial training of the canceller in a half-duplex mode;  (b) a 
draft proposal for a full-duplex multicarrier modem that operates at 
speeds up to 24,000 bits per second.

(3)  Codex/David Forney -- Two papers are in process:  (a) A 
single-carrier modem for V.fast: description and test results; 
presents a description of and test results for an implementation of 
a single-carrier high-speed duplex two-wire modem at data rates up 
to 24,000 bits per second.;  (b)  originally drafted by Codex and 
now sources by Codex, General Datacomm, AT&T, Octocom, Hayes, and
others, entitled Single-Carrier Modulation for V.fast; discusses the 
question of single-carrier vs. multicarrier modulation, and 
recommends focusing on single-carrier modulation for V.fast.

(4)  British Telecom/John Brownlie -- paper will address operating 
procedures for V.fast.  The aspects considered will include start-up 
times, automoding, training signals, rate signalling procedures, 
bandwidth estimation, and symbol-rate changing.

(5)  Intelligent Modem Corporation/Laura Preece -- paper will 
discuss an additional approach to multicarrier modulation, including 
solutions for cancellation of both near- and far-end echoes, and 
considerations for peak-to-average ratio and system delay.


The meeting will be lively, filled with facsinating discussions and 
arguments over the various proposals and papers.  Wish you could all 
be there!  It will certainly be interesting to finally see Telebit's 
proposal for echo cancellation in multicarrier modulation and 
Codex's proposal for single-carrier 24000 bit/s modulation (that's 
synchronous bit rate, without data compression, folks).

-- 
Toby Nixon, Principal Engineer    | Voice   +1-404-449-8791  Telex 151243420
Hayes Microcomputer Products Inc. | Fax     +1-404-447-0178  CIS   70271,404
P.O. Box 105203                   | UUCP uunet!hayes!tnixon  AT&T    !tnixon
Atlanta, Georgia  30348  USA      | Internet       hayes!tnixon@uunet.uu.net